Retractable sheath devices, systems, and methods

Abstract

The invention is directed to delivery medical devices that enable consistent “on-demand” delivery of therapeutic agents to a vessel. The medical device of the current invention comprises retractable sheath comprising neckable elements. The medical device of the current invention comprises an expandable member, a hydrophilic coating comprising at least one therapeutic agent about the expandable member or structural layer and a retractable outer sheath with a selectively permeable microstructure. The design and methods disclosed herein ensures that therapeutic agent delivery occurs essentially only during retraction of the outer sheath, minimizing coating and/or therapeutic agent loss to the bloodstream and providing controlled delivery to the treatment site.

What is claimed is: 
     
       1. A medical device comprising:
 an inflation port in fluid communication with a lumen of an expandable member, the expandable member having an uninflated diameter and being configured to expand to an inflated diameter; 
 a coating comprising a therapeutic agent disposed on the expandable member, wherein the therapeutic agent is complexed or sequestered by one or more solubilizing agents; and 
 a retractable outer sheath having a permeable microstructure comprising micropores, the retractable outer sheath disposed around the expandable member and over the coating; 
 wherein when the expandable member is exposed to a fluid while the expandable member is at the uninflated diameter, the micropores are configured to permit at least partial replacement of air within the micropores with the fluid so as to allow for the fluid to pass through the retractable outer sheath and hydrate the coating so as to form solubilized particles of the therapeutic agent, and restrict release of the solubilized particles through the retractable outer sheath to limit unintended transfer of the therapeutic agent, and 
 wherein inflation of the expandable member causes expansion of the micropores and exposes at least a portion of the hydrated coating, releasing the solubilized particles through the micropores. 
 
     
     
       2. The medical device of  claim 1 , wherein the retractable outer sheath comprises at least one of a dilatable slit or dilatable pore configured to dilate upon inflation of the expandable member. 
     
     
       3. The medical device of  claim 1 , wherein the retractable outer sheath comprises a frangible film configured to split open inflation of the expandable member. 
     
     
       4. The medical device of  claim 1 , wherein the retractable outer sheath comprises at least two adjacent film elements configured to separate upon inflation of the expandable member. 
     
     
       5. The medical device of  claim 1 , wherein the coating comprises a hydrophilic component. 
     
     
       6. The medical device of  claim 5 , wherein the hydrophilic component in the coating raises the solubility point of a hydrophobic therapeutic agent. 
     
     
       7. The medical device of  claim 1 , wherein the coating comprises at least one compound selected from the group consisting of benzethonium chloride, PEG, poloxamer, sodium salicylate, and hydroxypropyl-p-cyclodextrin. 
     
     
       8. The medical device of  claim 1 , wherein the therapeutic agent is a hydrophilic agent. 
     
     
       9. The medical device of  claim 1 , wherein the therapeutic agent is a hydrophobic agent. 
     
     
       10. The medical device of  claim 9 , wherein the hydrophobic agent is selected from the group consisting of taxane domain-binding drugs, such as paclitaxel, and rapamycin. 
     
     
       11. The medical device of  claim 1 , wherein the retractable outer sheath is treated with a wetting agent. 
     
     
       12. The medical device of  claim 11 , wherein the wetting agent is selected from the group consisting of heparin coatings, polyvinyl alcohol, polyethylene glycol, polypropylene glycol, dextran, agarose, alginate, polyacrylamide, polyglycidol, poly(vinyl alcohol-co-ethylene), poly(ethyleneglycol-co-propyleneglycol), poly(vinyl acetate-co-vinyl alcohol), poly(tetrafluoroethylene-co-vinyl alcohol), poly(acrylonitrile-co-acrylamide), poly(acrylonitrile-co-acrylic acid-co-acrylamidine), polyacrylic acid, poly-lysine, polyethyleneimine, polyvinyl pyrrolidone, polyhydroxyethylmethacrylate, and polysulfone, and their copolymers, either alone or in combination. 
     
     
       13. The medical device of  claim 11 , wherein the wetting agent is polyvinyl alcohol. 
     
     
       14. The medical device of  claim 1 , wherein the retractable outer sheath comprises a tetrafluoroethylene copolymer comprising a hydrophilic monomer. 
     
     
       15. The medical device of  claim 1 , wherein the retractable outer sheath comprises at least one material from the group consisting of a fluoropolymer, polyamides, polyurethane, polyolefins, polyesters, polyglycolic acid, poly lactic acid, and trimethylene carbonate. 
     
     
       16. The medical device of  claim 1 , wherein the retractable outer sheath comprises a fluoropolymer comprising the permeable microstructure. 
     
     
       17. The medical device of  claim 1 , wherein said the retractable outer sheath comprises ePTFE expanded polytetrafluoroethylene. 
     
     
       18. The medical device of  claim 1 , wherein the micropores restrict the release of particles greater than about 5 μm through the retractable outer sheath. 
     
     
       19. The medical device of  claim 1 , wherein the micropores restrict the release of particles greater than about 10 μm through the retractable outer sheath. 
     
     
       20. The medical device of  claim 1 , wherein the micropores restrict the release of particles greater than about 25 μm through the retractable outer sheath. 
     
     
       21. The medical device of  claim 1 , wherein the expandable member elastically expands to the inflated diameter. 
     
     
       22. A medical device comprising:
 an inflation port in fluid communication with a lumen of an expandable member, the expandable member having an uninflated diameter and being configured to expand to an inflated diameter; 
 a coating comprising a therapeutic agent disposed on the expandable member, and 
 a retractable outer sheath having a permeable microstructure comprising micropores, the retractable outer sheath disposed around the expandable member and over the coating; 
 wherein when the expandable member is exposed to a fluid while the expandable member is at the uninflated diameter, the micropores are configured to permit at least partial replacement of air within the micropores with the fluid so as to allow for the fluid to pass through the retractable outer sheath and hydrate the coating so as to form solubilized particles of the therapeutic agent and restrict release of the solubilized particles through the retractable outer, and 
 wherein when the expandable member is at a treatment site, the inflation port is configured to inflate and expand the expandable member to the inflated diameter, which causes the expansion of the micropores and exposes at least a portion of the hydrated coating, releasing the solubilized particles through the micropores.